Q: Have analysed storm window impact? financial and carbon foot print?

A: No because I have not added exterior storm windows. However, the purpose of exterior storm windows and interior-fitting window inserts is very different. Exterior storms protect the window frame and its paint from wind, rain and sun. But the air between the exterior storm and the real window is not sealed and it blows away with the breeze, hence it has very little insulating value. With little insulation benefit there is very little cost saving with exterior storm windows hence the reduction in carbon footprint and heating bill is likely to be very small. The purpose of interior-fitting window inserts is to stop drafts, add insulation and block noise. Because they are very effective at blocking drafts (see Chapter 4 in the book) and adding insulation window inserts will both cut your heating bill and carbon footprint. The financial payback is about 5 years. The increase in comfort of the room is immediate.